Multi-walled Carbon Nanotubes Support Research Articles

Impact of different isothermal aging conditions on the IMC layer growth and shear strength of MWCNT-reinforced Sn–5Sb solder composites on Cu substrate

In this study, the effect of multi-walled carbon nanotubes (MWCNTs) reinforcement on the intermetallic compound (IMC) layer growth and shear strength of Sn–5Sb-xCNT/Cu composite solder joints subjected to different isothermal aging conditions has been investigated. A series of plain and composite lead-free solder systems (Sn–5Sb-xCNT; x = 0, 0.01, 0.05 and 0.1 wt%) was successfully developed through the powder metallurgy method. Isothermal aging process was performed on the solder/Cu joints at 120 °C, 150 °C and 170 °C temperatures in order to investigate the evolution of the interfacial IMC layers and the shear strength property. Experimental results showed that the thickness of the total IMC layer increased with rising aging temperature. While the Cu3Sn IMC maintained a layer-type morphology for all aging conditions, morphology of the Cu6Sn5 IMC transformed from a scallop-type to a layer-type after aging at intermediate (150 °C) and high (170 °C) temperatures. Given the potential of MWCNTs as a reinforcement material, significant suppression in IMC layer growth was demonstrated by the composite solder joints relative to the plain counterpart. Comprehensive investigation on the growth kinetics showed that the presence of MWCNTs in the composite solder joints was effective in slowing down the diffusion mechanism responsible for IMC growth. Overall, the Sn–5Sb-0.05CNT composite solder joint exhibited the lowest diffusion coefficient within the range of 0.09 × 10−14- 1.03 × 10−14 cm2/s and 0.95 × 10−14- 9.8 × 10−14 cm2/s for Cu6Sn5 and Cu3Sn IMC layers respectively. Moreover, the strengthening effect of the MWCNTs reinforcement was well marked in the composite solder joints as the maximum shear strength within a range of 24.2–15.2 MPa was exhibited by the Sn-0.01CNT/Cu composite solder joint subjected to reflow soldering and isothermal aging conditions.

Multi-walled Carbon Nanotubes Reinforced into Hollow Fiber by Chitosan Sol-gel for Solid/Liquid Phase Microextraction of NSAIDs from Urine Prior to HPLC-DAD Analysis.

The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies. In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC-DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution. The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods. The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.

Optimizing Weight Percentage of MWCNTs for Enhancing LVI Resistance of Quasi-Isotropic Symmetric Laminate of Carbon Woven Fabric/ Epoxy Embedded with MWCNTs

This research work investigates the energy absorption, and damage tolerance behavior of three phased (carbon woven/epoxy/multiwall carbon nanotubes) polymer composites. Five doping weight fractions of multi-wall carbon nanotubes (MWCNTs) are considered as 0, 1, 2, 3 and 4 wt.% of thermosetting epoxy resins. Low-velocity impact (LVI) tests are conducted on drop tower setup with three different velocities, 3.5, 4.5 and 5.5 m/s. Damage caused by a 10 kg, hemispherical headed cylindrical impactor is analyzed and compared. The experimental results showed an increase in the energy absorption up to 3 wt.% of the MWCNT doping. However, reinforcing above this percentage, the energy absorption is reduced due to the formation of MWCNT agglomerations. Therefore, this work proposed an optimized doping percentage for CFRP laminates. The maximum improvement of 51.83% in energy absorption was found at 3 wt.% of MWCNT reinforcement in epoxy resins.

Functionalized Multi Walled Carbon Nanotubes-Reinforced Hollow Fiber Solid/Liquid Phase Microextraction and HPLC-DAD for Determination of Phenazopyridine in Urine

Introduction:A sensitive analytical method based on functionalized multi walled carbon nanotubes reinforced hollow fiber solid/liquid phase microextraction (F-MWCNTs-HF-SLPME) forwarded with HPLC-DAD for analyzing phenazopyridine from urine is presented.Materials and Methods:The extraction of phenazopyridine is performed using specially designed FMWCNTs- HF-SLPME device constructed as follows: the functionalized multi walled carbon nanotubes (F-MWCNTs) were immobilized into the pores of 2.5 cm hollow fiber micro-tube using capillary forces and ultrasonication, then, the lumen of the micro-tube was filled with 1-octanol with two ends sealed. Subsequently, the device was placed into 10-mL of urine sample containing the analyte with agitation. After ending extraction, the device was removed, rinsed, sonicated in 250 µL of organic solvent and analyzed directly by the separation system.Results and Conclusion:Different parameters affecting the performance of the developed method were optimized. The method showed good linearity with (R2) 0.999 and good repeatability with (RSDs) from 3.7 to 0.9% at analyte concentration ranged from 0.01 to 10 µg L-1 of spiked urine samples. The limit of detection/ quantitation, LODs/LOQs was 0.02/0.09 µg L-1. In comparison with reference methods, the developed method is considered as a promising microextraction technique for determination of trace phenazopyridine in human urine using a common HPLC without further cleanup procedures.

Effects of arrangement and shape of MWCNT and GNP reinforcements on nanocomposite mechanical properties

In this investigation, multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets were used to prepare two-phase and hybrid epoxy-based nanocomposites. Tensile and compressive mechanical pro...

Mechanical strength of single-lap joints bonded with nano graphene and MWCNT reinforced epoxy-based nanocomposite adhesives

Abstract Nanocomposites have attracted much attention from scientific and industrial areas in recent decades because of their mechanical, physical, thermal and barrier properties and unique design possibilities. These materials have been commercially used in the automotive, electronic, biomedical, packaging etc. industries and their usage areas have been increasing day by day. In this study, nanocomposite adhesives were produced by adding nano graphene and multi-walled carbon nanotube (MWCNT) particles to a single component epoxy adhesive at the ratios of 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1, 3 and 5 wt.-%. Then, these nanocomposite adhesives were used to prepare single-lap joints. Shear tests were performed to specify their adhesive shear strengths and joint tensile strengths. It was observed that mechanical strength increased to the reinforcement amount of 0.5 wt.-%. After that, the strength values decreased due to a tendency towards agglomeration, viscosity increment and due to a difficulty in homogeneously applying the adhesive. Furthermore, it was found that nano graphene reinforcement improved the mechanical strength of the epoxy-based adhesive slightly more than MWCNT reinforcement.

Material and Mechanical Characterization of Multi-Functional Carbon Nanotube Reinforced Hybrid Composite Materials

Fiber reinforced polymer (FRP) composite structures are widely being used in aircraft wings, wind turbine blades, helicopter rotor blades and tail rotors. These structures are often exposed to external dynamic loads which shorten their lifetime. Carbon nanotubes (CNT) reinforced epoxy resin have distinctive characteristic in providing a significant increase in mechanical properties and stiffness of the FRP composite. The present study investigates the micro, macro and structural analysis of composites with and without reinforcement of multi walled carbon nanotubes (MWCNT). The carboxylic acid (COOH) functionalized MWCNT with more than 95% chemical purity having average dimensions of 17 nm outer diameter and 10 μm length were used to characterize their chemical properties and evaluate the mechanical and free and forced vibration response of composites with and without MWCNT reinforcement. Initially, the powder form of the MWCNT was taken for the identification of true density (ρ) using the gas displacement technique. The COOH-MWCNT were then randomly dispersed in low viscosity epoxy resin (LY556) through an organic solvent using the ultrasonic liquid processor. Test samples were fabricated by adding the hardener (HY951) at 10:1 ratio in the sonicated solution to obtain the Young’s Modulus (E) of MWCNT using Nano Indentation. Following this, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared spectroscopy (FT-IR), Thermo gravimetric analysis (TGA) were also used to quantify the dispersion, distribution, structural integrity, aspect ratio, functional group and purity level of nanotubes. Further, the impact hammer test based on ASTM E1876, tensile test based on ASTM D3039 and free and forced vibration analysis of the hybrid composite beams were carried out to identify the elastic properties, fundamental natural frequencies, damping ratio and transverse deflection of the hybrid structure. It was shown that the addition of 1 wt% of COOH-MWCNT in fiber reinforced composite beam increases the stiffness of the structure and consequently increases the natural frequencies and damping at each resonant response dominant peaks. The strong adhesion of bonding and proper dispersion of CNTs in the wide surface area of composite strengthen the polymer composites substantially than those of the Glass/epoxy composite structures without reinforcement of MWCNT.

Effect of multi-walled carbon nanotubes on thermal stability and ablation properties of EPDM insulation materials for solid rocket motors

Multi-walled carbon nanotubes (MWCNTs) have excellent physicochemical properties and can be used as fillers to improve the performance of insulation materials. However, there is currently no proper understanding of the mechanism by which MWCNTs improve the ablation performance of insulation materials. Here, we prepare two formulations of ethylene propylene diene monomer (EPDM) insulation materials with and without MWCNTs and study their thermal stability and ablation characteristics via thermogravimetric analysis, high temperature char layer residue experiments, oxyacetylene ablation tests, and other analytical methods along with scanning electron microscopy and energy dispersive X-ray spectroscopy. The intrinsic mechanism by which MWCNTs improve the ablation performance of insulation materials is revealed from the perspectives of char layer formation, consumption, and micro-morphology. The addition of MWCNTs increased the carbon residue rate after thermal decomposition and can suppress the consumption reaction of the char layer under high-temperature conditions. Microscopic morphological analyses show that the insulation material containing MWCNTs has a denser char layer surface and a network-like structure inside, which improve the ability of the char layer to resist erosion by gas flow. The combination of these factors improves the ablation performance of EPDM. Our findings regarding the MWCNT reinforcement mechanism can guide the design of new insulation materials.

Effect of sonication in enhancing the uniformity of MWCNT distribution in aluminium alloy AA2219 matrix

Abstract The present paper investigates the effect of premixing process on the distribution of 0, 0.5, 0.75, 1 and 2 wt.% multiwall carbon nanotubes (MWCNTs) and resultant properties of aluminium alloy AA2219 matrix. Premixing process consists of ultrasonication, magnetic stirring and mechanical stirring. FESEM was used for characterizing the distribution of reinforcement in the matrix. Ball milling with premixing was found to be effective in achieving better uniform distribution of the reinforcement than mere ball milling. Hardness testing of the composite revealed reinforcement of MWCNT enhances the matrix hardness. The thermal stability of composite as evidenced by DTA analysis proved the presence of MWCNT without any structural damages.

Mechanical Behavior of Multiwalled Carbon Nanotube Reinforced 7075 Aluminum Alloy Composites Prepared by Mechanical Milling and Hot Extrusion

In this paper, multiwalled carbon nanotubes (MWCNTs) were synthesized by spray pyrolysis to be used later as material reinforcement in the production of MWCNTs/Al7075 aluminum composites. Both, MWCNTs and MWCNTs/Al7075 composites were microstructurally and mechanically characterized. Scanning electron microscopy (SEM) analysis shows MWCNTs formed by multiple layers rolled on themselves forming a tube shape with lengths up to 1300 µm and diameters ranging from 55 to 120 nm. MWCNTs were added to the aluminum matrix in different concentrations up to 3.0 wt%. Their dispersion in the aluminum matrix was carried out by ultrasonic/methanol method followed by high-energy mechanical milling process. The effect of MWCNTs on the morphology and mechanical behavior of composites were evaluated. Results indicate that a homogeneous dispersion of CNTs was obtained as a consequence of the dispersion routes used in the production of composites, observing no damage on their morphology. The mechanical behavior of the composites shows a noticeable improvement for MWCNTs concentrations above 2.0 wt%, with ductility similar to that found in the literature for the Al7075 commercial alloy.

Theoretical deflection analysis of multi-walled carbon nanotube reinforced sandwich panel and experimental verification

In this article, the influence of the multi-walled carbon nanotube reinforcement on the stiffness of sandwich curved panel is examined theoretically via deflection analysis and compared with own experimental data for the verification of accuracy. The nanotube-reinforced sandwich structural panel model is derived theoretically using the higher-order polynomial functions and displacement finite element steps adopted for the numerical solution purpose. The structural stiffness values are measured from the deflection resistance of the theoretical structural model by computing the structural equilibrium equation with the help of an own customized MATLAB code. Firstly, the numerical solution accuracy and the corresponding reliability of the present solutions are cross-checked through the element sensitivity including the comparison test. Further, the multi-walled carbon nanotube reinforced sandwich plate is fabricated for the required experimentation including the mechanical as well as the material characterization. Finally, the validity of theoretically predicted deflection data of sandwich structure demonstrated by comparing with the own experimental results. In addition, the effect of various design parameters on the stiffness behavior of the own fabricated sandwich construction is computed using the proposed theoretical model and discussed in detail.

A one-pot strategy for preparation of high-strength carboxymethyl xylan-g-poly(acrylic acid) hydrogels with shape memory property

High strength hydrogels open new possibilities in the fields of bioengineering and biomedical. In this paper, a highly efficient one-pot strategy was developed to prepare carboxymethyl xylan-g-poly (acrylic acid) (CMX-g-PAA) hydrogels with high compression strength, high elongation and high elasticity by using the metal coordination and the reinforcement of hydroxylate multi-walled carbon nanotubes (HCNTs). Prepared hydrogels were characterized by means of FTIR, XRD, SEM, rheological measurements as well as their swelling and mechanical properties. Results showed that the Fe3+-carboxyl coordination and HCNTs imparted hydrogels with high strength and good rapid recovery properties, in which the maximum high compressive strength and elongation at break were achieved to 10.4 MPa and 1032%, and the shape of hydrogels almost returned to the original shape after the external force was removed after 30 cycles of compression. These hydrogels also exhibited Fe3+-triggered shape memory properties. Therefore, as-prepared hydrogels possessing high strength, rapid recovery and shape memory properties, could broaden access for application in intelligent toys, electronic skin, biosensing, and tissue engineering.

Improvements in mechanical properties of SPS processed 15R-SiAlON polytype through structurally survived MWCNT reinforcement

Abstract Present work reports the effects of multiwalled carbon nanotube (MWCNT) reinforcement on sintering and mechanical properties of additive free, dense (>96%) 15R-SiAlON polytype. Laboratory made precursor polytype powder, prepared through carbothermal-reduction-nitridation technique and devoid of any external sintering additive, were dispersed with MWCNT and were consolidated using spark plasma sintering at 2000 °C for 10 min under 40 MPa. Differential electrical conductivity causing localized heating resulted in improved sintering behaviour in the composites. Apart from formation of both equiaxed and elongated SiAlON grains, various CNT/SiAlON interactions were noticed in the composites. Depending on test load, the 0.5 wt% MWCNT/15R-SiAlON composite offered 9.6–17% and 12–13% higher hardness and indentation fracture toughness, respectively, over the monolith. Indentation size effect and load dependence of indentation toughness of the studied specimens have been reported. Under 20N, >30% reduction in specific wear rate was observed at only 0.5 wt% MWCNT loading. Self-reinforcement offered by elongated matrix grains, reinforcement by structurally survived CNTs, matrix grain refinement by the dispersed nanotubes and solid lubrication offered by the pulled-out CNTs were the key factors behind obtaining improved tribo-mechanical performance of the composites over pure 15R-SiAlON polytype.

Synergistic effect of welding electrospun fibers and MWCNT reinforcement on strength enhancement of PAN–PVC non-woven mats for water filtration

Typical electrospun polymer mats exhibit poor mechanical properties, undesirable for pressure-driven water filtration. Herein, strength enhancement of polyacrylonitrile–poly(vinyl chloride) (PAN–PVC) electrospun mats is demonstrated with a synergistic approach, using solvent vapor-induced welding of the polymer fibers at their cross points and reinforcement of the fibers by unfunctionalized multi-walled carbon nanotubes (MWCNTs). Tensile strength and Young’s modulus of the as-spun PAN–PVC mats are increased by 127% and 175% respectively via welding effects, and are further enhanced to 205% and 314% increments respectively, using 1 wt% MWCNTs. The post-treated composite mats achieve over four-fold the modulus predicted by the modified Halpin–Tsai model. With a slight total reduction in pure water flux (8%), water permeability is not greatly suppressed by welding the polymer fibers or by the presence of MWCNTs in the fibers. The two strength-enhancing strategies also allow recyclability of the post-treated composite mats with high particulate (25 nm–5 μm) filtration efficiency of nearly 100% and good antifouling performance (flux recovery of >93%) throughout the 10 tested filtration cycles.

Surfactant assisted synthesis of Pt-Pd/MWCNT and evaluation as cathode catalyst for proton exchange membrane fuel cell

This study evaluates the role of two types of surfactants, the anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) on the synthesis and properties of multi-walled carbon nanotube (MWCNT) supported bi-metallic Pt-Pd (atomic ratio 1:1) nanoparticles (NPs) and assess their performance as cathode catalyst in proton exchange membrane fuel cell (PEMFC). Pt-Pd/CNT catalysts are prepared through microwave assisted, polyol route in presence of SDS (Pt-Pd/CNT-S) or CTAB (Pt-Pd/CNT-C) and their performance is compared with Pt-Pd/CNT prepared in an identical way without any surfactant. The study shows the prominent influence of the type of surfactant in disaggregation of MWCNT bundles and the dispersion of Pt-Pd NPs on MWCNT support, which in turn controls their catalytic activity for oxygen reduction reaction. In-situ electrochemical characterization studies show improvement in the catalytic activity of Pt-Pd/CNT-S compared to Pt-Pd/CNT-C and Pt-Pd/CNT, demonstrating SDS as an efficient disperser for MWCNT. High fuel cell performance achieved with Pt-Pd/CNT-S having less Pt content (∼12 wt %) than the commonly employed pure Pt or Pt/C (20 wt %) catalysts demonstrates that it is a potential cathode catalyst for PEMFC that can help its wider commercialization.

Carbon nanotubes reinforced reactive powder concrete

In this paper, four types of multi-walled carbon nanotubes (MWCNTs) were incorporated into reactive powder concrete (RPC) with water or heat curing. The enhancing effects of MWCNT types and curing methods on mechanical properties of RPC were investigated. Experimental results indicate that adding proper type and content of MWCNTs can effectively improve mechanical properties of RPC including flexural strength, fracture energy, compressive strength/toughness and flexural strength to compressive strength ratio. In general, these mechanical properties of MWCNTs filled RPC with heat curing are superior to that with water curing, which indicates that heat curing is more beneficial for reinforcing impact of MWCNTs to RPC than water curing. In most cases, the critical length of MWCNTs in RPC is smaller than actual length, which indicates MWCNTs will be snapped when damage occurs in RPC. In addition, the reinforcement of MWCNTs to RPC results from crack bridging and pull out effects.

Effect of MWCNTs on piezoelectric and ferroelectric properties of KNN composites

The aim of the research work was to investigate the effect of multiwall carbon nanotubes (MWCNTs) reinforcement (0.3–1.2wt.%) on functional properties of microwave sintered Potassium sodium niobate (KNN) composites. Sintered composites are characterized for crystal structure, morphology and temperature stability of piezo-electric, ferroelectric and dielectric properties. KNN composites showed perovskite phase with improved tetragonal symmetry, fine grained porous microstructure, reduced dielectric loss and enhanced effective permittivity. The optimum functional properties and thermal stability obtained for KNN-MWCNT (0.9 wt.%) composites over the range of 20–100 °C, makes the idea of using the addition of MWCNTs to KNN ceramics an interesting approach in searching new structures for temperature stability.

The influence of topology and morphology of fillers on the conductivity and mechanical properties of rubber composites

Herein, the comparison of butadiene rubber (BR) composites based on the thermally reduced graphene (TrG), multi-walled carbon nanotubes (MWCNTs) and carbon black (CB) on conductivity and mechanical properties was reported. SEM images of the composites showed that the TrG exhibited better dispersion and compatibility with the BR matrix than that of MWCNTs and CB. Therefore, a significant enhancement of electrical conductivity and mechanical properties of the BR/TrG nanocomposites were obtained at low graphene content. The electrical conductivity of the BR/TrG nanocomposites increased from 1 × 10−13 S cm−1 to 1.8 × 10−4 S cm−1 in the presence of 7 phr TrG and the electrical percolation threshold was about 4.3 phr, compared with 9.5 phr and 44 phr for MWCNTs and CB, respectively. A 448% improvement of tensile strength and a nearly 2 times improvement of elongation at break were obtained at the graphene content of 7 phr. Compared with the MWCNTs and CB, the content of graphene in composites was much lower than that of MWCNTs and CB when the mechanical properties was similar. The dynamic mechanical properties showed that the TrG efficiently reinforced the storage modulus and reduced the loss factor of the composites relative to MWCNTs and CB. The different reinforcement of TrG, MWCNTs and CB mainly came from the different topology and morphology of the three fillers. Different contact specific area provided different interface interaction, which induced the different dispersity, which influenced the properties of the composites at last.

MWCNTs toward superior strength of epoxy adhesive joint on mild steel adherent

Abstract In this work, the characteristics of the lap shear joints of MWCNT-epoxy adhesive on mild steel adherend are investigated. In this paper, multiwall carbon nanotubes (MWCNTs) are homogeneously and cluster-freely reinforced in epoxy matrix by simultaneously applying ultrasonic waves and an axial flow impeller on epoxy resin to develop toughened epoxy adhesives. Here, we describe details pertaining to mild steel surface morphology, the bond line thickness of the adhesive, the wettability of MWCNT-epoxy resin on the mild steel surface and the impact of the presence of MWCNTs in epoxy resin on the performance of lap shear joints. The experimental observations indicate that the reinforcement of MWCNTs in epoxy with uniform cluster-free dispersion and a change in the morphology of the mild steel adherend significantly improve the strength of lap shear joints and change their failure mode. The inclusion of 0.75 wt% of MWCNTs in epoxy adhesive resulted in the largest enhancement in the lap shear strength and as the weight percentage of MWCNTs increased from 0.75 wt%, the lap shear strength began to degrade.

Effect of MWCNT reinforcement on the precipitation-hardening behavior of AA2219

Aluminum alloy matrix composites have found a predominant place in research, and their applications are explored in almost all industries. The aerospace industry has been using precipitation-hardenable alloys in structural applications. However, insufficient literature is available on the influence of multiwalled carbon nanotubes (MWCNTs) on precipitation-hardenable alloy composite materials; thus, this work was designed to elucidate the effect on MWCNT reinforcement on AA2219 with and without precipitation hardening. Reinforcement with MWCNTs has been reported to accelerate precipitation and to achieve greater hardness within a much shorter time. The addition of 0.75wt% MWCNTs resulted in maximal hardness at 90 min, which is approximately 27% of improvement over the maximum hardness achieved by the corresponding monolithic alloy after 10 h of aging. The sample reinforced with 0.75wt% MWCNTs showed an improvement of 82% in hardness by solutionizing and aging compared to that achieved by sintering.